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osmo-ttcn3-hacks
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bsc: split f_verify_encr_info() from f_cipher_mode() 

The verification of correct encryption information so far is part of
f_cipher_mode(); put it in a separate new function f_verify_encr_info()
so that it can be re-used for handover channel activation.

Related: SYS#5324
Change-Id: I11602d23670f436a22b891fc744fe07e470f2b79
This commit is contained in:
Neels Hofmeyr 2021-06-21 02:17:30 +02:00 committed by laforge
parent 3fe8460494
commit 58ffceb4ec
1 changed files with 59 additions and 30 deletions
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89
bsc/MSC_ConnectionHandler.ttcn
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@ -713,12 +713,65 @@ function f_chipher_mode_bssmap_to_rsl(OCT1 alg_bssmap) return RSL_AlgId
}
}
function f_verify_encr_info(RSL_Message rsl) runs on MSC_ConnHdlr {
var RSL_IE_Body encr_info;
var RSL_AlgId alg_rsl;
var template octetstring expect_kc;
/* If no encryption is enabled, then make sure there is no RSL_IE_ENCR_INFO */
if (not ispresent(g_pars.encr)) {
if (f_rsl_find_ie(rsl, RSL_IE_ENCR_INFO, encr_info)) {
setverdict(fail, "Found Encryption IE, but expected no encryption in ", rsl.msg_type);
Misc_Helpers.f_shutdown(__BFILE__, __LINE__);
return;
}
setverdict(pass);
return;
}
/* RSL uses a different representation of the encryption algorithm,
* so we need to convert first */
alg_rsl := f_chipher_mode_bssmap_to_rsl(g_pars.encr.enc_alg);
if (alg_rsl == RSL_ALG_ID_A5_4 and ispresent(g_pars.encr.enc_kc128)) {
expect_kc := g_pars.encr.enc_kc128;
} else if (alg_rsl == RSL_ALG_ID_A5_0) {
/* When A5/0 is chosen, no encryption is active, so technically, no key is needed. However, 3GPP TS
* 48.058 9.3.7 Encryption Information stays quite silent about presence or absence of a key for A5/0.
* The only thing specified is how to indicate the length of the key; the possibility that the key may
* be zero length is not explicitly mentioned. So it seems that we should always send the key along,
* even for A5/0. Still, let's also allow a zero length key for A5/0. */
expect_kc := (g_pars.encr.enc_key, ''O);
} else {
expect_kc := g_pars.encr.enc_key;
}
log("for encryption algo ", alg_rsl, " expect kc = ", expect_kc);
if (not f_rsl_find_ie(rsl, RSL_IE_ENCR_INFO, encr_info)) {
if (alg_rsl == RSL_ALG_ID_A5_0) {
/* For A5/0, encryption is not active. It is fine to omit the Encryption Information in this
* case. Note that the first channel may see an RSL Encryption Command with A5/0 indicated, and
* a subsequent handover may activate a new channel without any Encryption Information. */
setverdict(pass);
return;
}
setverdict(fail, "Missing Encryption Information IE in ", rsl.msg_type);
Misc_Helpers.f_shutdown(__BFILE__, __LINE__);
return;
}
if (not match(encr_info, tr_EncrInfo(alg_rsl, expect_kc))) {
setverdict(fail, "Unexpected Kc in Encryption Information IE in ", rsl.msg_type);
Misc_Helpers.f_shutdown(__BFILE__, __LINE__);
return;
}
setverdict(pass);
}
function f_cipher_mode(TestHdlrEncrParams enc, boolean exp_fail := false)
runs on MSC_ConnHdlr {
var PDU_BSSAP bssap;
var RSL_Message rsl;
var RSL_AlgId alg_rsl;
var template octetstring expect_kc;
if (isvalue(enc.enc_kc128)) {
BSSAP.send(ts_BSSMAP_CipherModeCmdKc128(enc.enc_alg, enc.enc_key, valueof(enc.enc_kc128)));
@ -726,39 +779,14 @@ runs on MSC_ConnHdlr {
BSSAP.send(ts_BSSMAP_CipherModeCmd(enc.enc_alg, enc.enc_key));
}
/* RSL uses a different representation of the encryption algorithm,
* so we need to convert first */
alg_rsl := f_chipher_mode_bssmap_to_rsl(enc.enc_alg);
if (alg_rsl == RSL_ALG_ID_A5_4 and ispresent(enc.enc_kc128)) {
expect_kc := enc.enc_kc128;
} else if (alg_rsl == RSL_ALG_ID_A5_0) {
/* When A5/0 is chosen, no encryption is active, so technically, no key is needed. However, 3GPP TS
* 48.058 9.3.7 Encryption Information stays quite silent about presence or absence of a key for A5/0.
* The only thing specified is how to indicate the length of the key; the possibility that the key may
* be zero length is not explicitly mentioned. So it seems that we should always send the key along,
* even for A5/0. Still, let's also allow a zero length key for A5/0. */
expect_kc := (enc.enc_key, ''O);
} else {
expect_kc := enc.enc_key;
}
log("for encryption algo ", alg_rsl, " expect kc = ", expect_kc);
alt {
/* RSL/UE Side */
[] RSL.receive(tr_RSL_ENCR_CMD(g_chan_nr, ?, alg_rsl, ?)) -> value rsl {
[] RSL.receive(tr_RSL_ENCR_CMD(g_chan_nr)) -> value rsl {
var PDU_ML3_NW_MS l3 := dec_PDU_ML3_NW_MS(rsl.ies[3].body.l3_info.payload);
log("Rx L3 from net: ", l3);
var RSL_IE_Body encr_info;
if (not f_rsl_find_ie(rsl, RSL_IE_ENCR_INFO, encr_info)) {
Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, "Missing Encryption IE in RSL ENCR CMD");
} else {
if (not match(encr_info, tr_EncrInfo(alg_rsl, expect_kc))) {
Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
"Unexpected Kc in Encryption IE in RSL ENCR CMD");
}
}
f_verify_encr_info(rsl);
if (ischosen(l3.msgs.rrm.cipheringModeCommand)) {
f_rsl_reply(ts_RRM_CiphModeCompl, rsl);
}
@ -769,6 +797,7 @@ runs on MSC_ConnHdlr {
Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, "Unexpected Cipher Mode Complete");
} else {
setverdict(pass);
var RSL_AlgId alg_rsl := f_chipher_mode_bssmap_to_rsl(g_pars.encr.enc_alg);
if (oct2int(bssap.pdu.bssmap.cipherModeComplete.chosenEncryptionAlgorithm.algorithmIdentifier) != enum2int(alg_rsl)) {
setverdict(fail, "Unexpected Encryption Algorithm ID in BSSMAP Cipher Mode Complete");
}